The productivity for an intermediate output should therefore rise until the required quantity is reached and the input cost of producing this quantity is minimized.

For example, the output quantity for wheelbarrows depends on the output quantities for final outputs (and other intermediate outputs) that require soil, sand, and other materials to be moved manually. Productivity must be high enough to permit this many wheelbarrows to be manufactured given the available labor force.

If this is not possible, and if workers cannot be diverted from other tasks to wheelbarrow production, then the output quantities for the associated final outputs will have to be scaled back. Assuming that the required number of wheelbarrows can be produced, productivity should be increased so as to minimize input cost.